Severe Thunderstorm Warning 34, NWS Raleigh, NC

AREA FORECAST DISCUSSION
National Weather Service Raleigh NC
255 PM EDT Sun May 01 2022

.SYNOPSIS...
A surface trough will approach from the west this afternoon and will
drift SE into the area overnight. The surface trough will then stall
out across central NC, while undergoing gradual weakening through
Tuesday.

&&

.NEAR TERM /TODAY THROUGH TONIGHT/...
As of 255 PM Sunday...

...A Severe Thunderstorm Watch Has Been Issued for northern portions
of the NC Piedmont and Coastal Plain counties through 9 pm...

...Damaging wind gusts and large hail will be the primary threat...

Located on the leading, southern edge of the closed low and upper
trough moving east into the Great Lakes and Ohio Valley, a string of
convectively enhanced upper-level impulses are currently moving east
across the central and southern Appalachians, and will move through
the region during the late afternoon and evening hours. The warm
front has lifted north into VA, leaving all of central NC firmly in
the warm sector. The seasonably strong insolation, coupled with a
weakening mid-level cap has allowed for moderate
destabilization(MLCAPE 1050-2000 J/Kg) across the NC Piedmont
counties.

Thus far, the convection over the NC mtns is rather scattered.
However, as the storms move into the more favorably unstable air
over the western Piedmont, the convection could potentially congeal
and become better organized. The convection and any severe threat is
expected to weaken/decrease with loss of heating and as storms move
east into a less favorable thermodynamic environment. With that
said, it's difficult to ascertain just how far east and south the
better risk of storms will extend. For now, the greatest threat
appears to be across the NW Piedmont and Triad.

Additionally, some of the models also indicate the potential for
some secondary convective re-development during the late evening and
overnight hours, as the weakening surface front and/or outflow
drifts SE into the area. Thus, will hang on to PoPs well into the
overnight hours.

Pockets of higher rainfall amounts of 0.50-0.75" will be possible
where the stronger convection across the NW Piedmont. Otherwise,
rainfall amounts are expected to be spotty and generally light.

Lows tonight in the upper 50s in the lower 60s.

&&

.SHORT TERM /MONDAY AND MONDAY NIGHT/...
As of 252 PM Sunday...

Mid-level heights will quickly rebound on Monday as shortwave
ridging spreads east into the area during the later half of the day.
Meanwhile, a weak surface boundary/trough will meander across
central NC. Low-level thicknesses are forecast to increase 5-8
meters compared to today, which should translate into 2 to 3 degrees
or warming, highs in the mid to upper 80s, warmest south.

Aside from some widely scattered seabreeze-related convection across
the far SE zones, where capping is weaker and where the tongue of
higher theta-e air will reside, expect dry conditions. Lows Monday
night ranging from mid/upper 50s to lower/mid 60s south.

&&

.LONG TERM /TUESDAY THROUGH SUNDAY/...
As of 148 PM Sunday...

The synoptic pattern at mid-levels will feature a mid-level
shortwave over the Mid-Mississippi Valley early Tue, that will track
into the Ohio Valley and Mid-Atlantic Tue night and early Wed.
Ridging over the Carolinas will shift offshore during the day as
weak impulses of energy track through NC in the aftn/eve in the
southwest flow. At the surface, a weak surface trough will be draped
from west to east across the Piedmont and northern Coastal Plain
early Tue, lifting north into VA during the day. Strong surface
heating with low-level thicknesses near 1410 m in the Sandhills and
Piedmont will lead to very warm temperatures in the upper 80s to
lower 90s. Current SSTs along the NC coast are in the upper 60s per
12Z RTOFS analysis, resulting in a temperature contrast of over 20
degrees. A favorable surface flow from the southwest will allow a
sea-breeze to build inland over the Coastal Plain in the afternoon.
In addition, guidance seems to be hinting on a Piedmont trough
developing with the strong surface heating in the Sandhills, which
could enhance convergence with the inland penetrating sea-breeze.
This will lead to a good chance of showers/storms along/east of US-1
in the aftn/eve with MLCAPE upwards of 1500 J/kg and dewpoints in
the lower 60s. Shear is not impressive, highest in the northern
Coastal Plain of about 25 kts, but some isolated damaging winds are
possible in the stronger cells. Additional convection is possible in
the northwest Piedmont with the mid-level impulses tracking in from
the southwest. Convection should dissipate in the late
evening/overnight with loss of daytime heating. Overnight lows will
be very mild, near record high minimums in the mid to upper 60s.

On Wed, we are still tracking a surface cold front diving southeast
from the Ohio Valley into the Carolinas by early Thu. The airmass is
largely unchanged from Tue, with upper 80s to lower 90s still
expected. The sea-breeze may again be a player, along with a
Piedmont trough with the hot temperatures in the Sandhills, ahead of
the cold front. Instability from the ECMWF EFI is showing some
anomalous values, with the deterministic models indicating SBCAPE
values upwards of 2500 J/kg. While shear is marginal, these
conditions would support hail and locally damaging winds. Otherwise,
expect convection to develop in the aftn/eve, tapering off by late
evening/overnight with the passage of the trough axis/front.

Thu-Sun: There remains uncertainty with the passage of the cold
front, with the GFS continuing its trend of keeping the front only
along the VA border early Thu, while the previous ECMWF/Canadian
bring it further south along central SC. The latter models have
support from the ensemble guidance, indicating drier conditions and
the next mid-level trough well west of NC in the central Plains as
opposed to the GFS position over the Midwest. Have kept Thu mainly
dry as a result, consistent with previous forecast package, and
temperatures cooler in the low to upper 80s.

The best chance of showers/storms appears Fri-Sat as model/ensemble
consensus is appearing to converge on the mid-level trough over the
central Plains to shift into the OH/TN Valley Fri night and Mid-
Atlantic/Carolinas Sat, eventually offshore sometime Sunday. There
remain differences on timing and pattern/orientation of the trough
amongst the ensemble guidance, but good forcing for ascent and
divergence aloft looks to be in place late Fri and Sat. As for
severe potential, details will largely depend on the overall setup,
but stronger deep-layer shear and favorable instability could
support severe storms late Fri-early Sat with an approaching front
and a possible surface low tracking along NC/VA. Temperatures should
trend from above average to below normal from the 70s/80s Fri to the
70s by Sun with clouds/precipitation and a cooler airmass behind the
front.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
As of 140 PM Sunday...

A cluster of storms is expected to develop over western NC and move
east near the VA/NC border this afternoon into this evening, most
likely affecting KINT/KGSO between 20-00z, then KRDU from 00-04z,
then finally KRWI from 01-05z. The southern extent of this cluster
of storms remains uncertain, but may reach KFAY between 03-07z. Some
guidance indicates showers/storms lingering over the area through
09z, but confidence is low on the location/intensity of these
lingering showers/storms given they will be dependent on the
evolution of the earlier cluster of storms. Skies will briefly clear
behind the exiting storm system before MVFR/IFR fog/stratus develops
over areas in which had the most rainfall, giving KGSO/KINT/KRDU the
best chance to see this solution develop. VFR conditions will return
for the remainder of the TAR period after the fog/stratus burns off
shortly after sunrise Monday morning.

Looking beyond 18z Monday, an active pattern is beginning to emerge
through Friday. Diurnal showers/storms will be possible Tuesday with
more widespread showers/storms on Wednesday as a cold front moves
through. Aviation restrictions will again be possible on Friday as
showers/storms will start to overspread the area as a storm system
moves through the OH/TN Valley.

&&

.RAH WATCHES/WARNINGS/ADVISORIES...
None.

&&

SYNOPSIS...CBL/Kren
NEAR TERM...CBL
SHORT TERM...CBL
LONG TERM...Kren
AVIATION...Swiggett/CBL

Hazardous Weather Outlook
National Weather Service Raleigh NC
144 PM EDT Sun May 1 2022

NCZ007>011-021>028-038>041-043-076-021745-
Person-Granville-Vance-Warren-Halifax-Forsyth-Guilford-Alamance-
Orange-Durham-Franklin-Nash-Edgecombe-Davidson-Randolph-Chatham-Wake-
Wilson-Lee-
144 PM EDT Sun May 1 2022

...SEVERE THUNDERSTORM WATCH 167 IN EFFECT UNTIL 9 PM EDT THIS
EVENING...

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...This afternoon and tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the
Internet for more information about the following hazards.

   Severe Thunderstorm Watch.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

There is a low probability for widespread hazardous weather.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

NCZ042-073>075-077-078-083>086-088-089-021745-
Johnston-Stanly-Montgomery-Moore-Harnett-Wayne-Anson-Richmond-
Scotland-Hoke-Cumberland-Sampson-
144 PM EDT Sun May 1 2022

This Hazardous Weather Outlook is for central North Carolina.

.DAY ONE...This afternoon and tonight.

An isolated strong to severe storm is possible this afternoon and
evening.

.DAYS TWO THROUGH SEVEN...Monday through Saturday.

There is a low probability for widespread hazardous weather.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

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